[THEORY] Game Slowdown
Why...
Game Slowdown
Simple explanation: entities get stuck trying to navigate between towers. Cpu cycles are being spent on each entity, trying to figure a way around the map. As entities build up, cpu power is increasingly devoted to solving unsolvable dilemmas - the greater the traffic jam, the slower the game runs.
Unclog the jam, return the speed. I`ve seen this issue many times before with other games. Same circumstance, same results.